Doktorsavhandling, 2012

In this thesis, possibilities to reduce emissions from combined cycle gas turbine (CCGT) plants are evaluated. The evaluation is done from two perspectives: techno-economic analysis, and analysis of the resource and integration potentials. Included technologies for reducing CO2 are biomass and concentrating solar power (CSP), integrated with the CCGT, as well as application of post-combustion carbon capture and storage (CCS) to the gas plant. The techno-economic analysis is based on technical options and methodology presented in three papers (Papers I, II and IV) and these options are in the thesis compared with a harmonized methodology. European potentials for integration with existing CCGT plants are assessed in the thesis by complementing database information for gas plants with solar irradiation data and satellite images. An analysis of the global material constraints of CSP is included, based on results from Paper III, and complemented with an oversight of material issues for biomass power and CCS. In addition, the thesis includes an oversight of global and European resource potentials of biomass power, CSP and CCS, based on literature review.
One main conclusion of the thesis is that there are potential efficiency and cost benefits of integrating biomass and solar energy with existing natural gas-fired power plants. Solar and biomass options are both found to give up to 8-13%-points better efficiency when integrated with a triple pressure CCGT plant, than corresponding stand-alone configuration. CCS in gas plants is found to have the lowest levelized cost of electricity, LCoE (60-80 EUR/MWh), compared to biomass-based options (80-140 EUR/MWh) and stand-alone solar (>200 EUR/MWh). Biomass-gas hybrids are, however, found to be competitive with CCS options in terms of CB-E, break-even cost of CO2. Integrating CSP collectors with combined cycle plants will reduce the LCoE to almost half that of stand-alone plants (~130 EUR/MWh), nearly closing the gap to where CSP can be competitive with other low-carbon technologies.
The total economic potential for biomass power is found to be about 1,000-3,000 TWhe/y in the EU. Comparable figures for CSP are 2,000-3,000 TWhe/y. The EU CO2 storage capacity is sufficient to facilitate more than 3,000 TWhe/y from natural gas CCS over a 100 year period. The European integration potential with CCGT plants is estimated to about 240 TWhe/y for biomass and 2-4 TWhe/y for concentrating solar. Material constraints should not be restrictive for significant growth or global capacity of the studied technologies. Integrating with existing CCGT plants can be viewed as a “low-hanging fruit” to reduce CO2 emissions, and build capacity and develop solar and biomass technologies.